High intensity discharge (“HID”) lamps, such as metal halide or electrodeless plasma discharge lamps, provide a high efficacy light source and are widely used in the lighting industry. When an HID lamp is cool, the pressure in the arc tube is low and has a relatively low resistance. To start the lamp a ballast or other starting device provides a starting voltage to the lamp that is high enough to start the lamp at this relatively low resistance. Once the lamp is on, its temperature increases so that when the lamp is operating at its normal operating temperature the pressure in the arc tube is high and requires a much higher starting voltage than when the lamp is cool. If the lamp goes off due to a power interruption, then when power is restored the ballast or other starting device attempts to restart or restrike the lamp. The restrike attempts begin when the lamp is close to its normal operating temperature, but the lamp will not restart because the starting voltage provided by the ballast is too low. As the lamp cools, the pressure in the arc tube drops and eventually the pressure drops enough that the lamp can be restarted. The time between the lamp turning off and the time to restart the lamp is called the restrike time and typically ranges from 15 to 45 minutes.
One method to reduce the restrike time is to use a ballast that can provide a voltage which is high enough to restrike the lamp at a higher pressure. These types of ballasts are expensive, have a relatively short lifespan, and are associated with safety issues.
Another method to reduce the restrike time is to use a full-time cooling system. One example of a full-time cooling system is a fan that circulates air between the lighting apparatus and the surrounding environment, such as that used in an indoor projection system. However, for some applications, such as industrial lighting fixtures and outdoor lighting fixtures, full-time cooling is not practical due to the expense of operating the cooling system, the risk that circulating air from the surrounding environment may introduce contaminants into the luminaire, or other reasons.